Process of refining copper.



E. C. KING.

PROCESS OF REFINING COPPER.

APPLICATION FILED OCT. 22. 1910. 7 1,183,736.

Patented May 16, 1916.

P I II),

rnocnss or nnrmrne corrnn.

Specification of Letters Patent.

Patented May 16, 1916.

Application filed October 22, 1910. Serial No. 588,531.

To all whom it may concern) Be it known that I, EDWARD C. KING, a

citizen of the United States, residing at be applied effectively to the molten copper 1n furnaces or vessels of any construction which afi'ord suflicient space for the escape of the gases evolved during the purifying operation, the molten copper during this operation being protected as far as practicable from oxidizing influences; As the impurities in the copper have a greater affinity for the carbon in the oil than they have for the copper, they immediately combine, the combined carbon and impuritles rising to the surface of the bath owing to their lower specific gravities. The volatile gases or substances pass off while the solids form a slag on the surface of the bath andmay be readily skimmed off by the operator when the hydrocarbon oil has eliminated all impurities from the copper, except the oxygen.

The final stage of the first operation may be determined by taking samples from the bath during the treatment and testing such samples by splitting them and examining the nature of the fracture, the skill and experience of the operator indicating when all impurities, except the oxygen, have been eliminated. However, according to the present invention, it is not so essential to determine the point where all impurities, ex-

cept the oxygen, have been eliminated as is the. case when the common method of oxidizing the impurities is employed for the rea son that copper has a very strong aflinity for oxygen, oxygen being the last impurity to be eliminated from the copper and therefore the oxygen injected into the molten bath .of metal for the purpose of eliminating the impurities in the copper is taken up largely by the copper itself and oxids and sub-oxids are formed. The presence of oxygen in copper is objectionable for the reason that it destroys its ductility and tensile strength, making the copper in such condition unmarketable. In order to properly refine the copper, all the oxygen injected into the coppenfor the purpose of removing the impurities must be eliminated from the copper, and this has been accomplished heretofore by the only method of'de-oxidizing copper new 1n use on-a commercial scale, that is to say, the insertion of poles of hard or soft wood into the bath of molten metal.

From the foregoing it will be readily observed that the injection of oxygen into a bath of molten copper for the purposes above stated is not a true method, for the effect of the introduction of oxygen is not only to eliminate impurities, but it introduces oxygen into the metal which has the effect of destroying its ductility and strength and this oxygen must be removed in order to render the copper marketable.

According to the present invention hydrocarbon 011, preferably crude petroleum, is introduced directly into the body of the copper While in a molten condition, and this hydrocarbon oil not only acts to eliminate gaseous or metallic impurities without inury to the copper, but after all impurities, excepting oxygen, have been removed and the bath is protected from all oxidizing influences by covering the bath with carbonaceous material not containing impurities that could be taken up by the metal, continuation of the operation of introducing hydrocarbon oil directly to the body of the molten copper forming the bath expels the last impurity, namely, oxygen, and when the oxygen has been expelled, the purifying operation is at an end. The carbon being injected, according to the present invention, before any 'oxidizing operation, and being a substitute for the universal practice of oxidizing the copper for the purpose of removing other impurities, it avoids the serious disadvantage arising from the fact that oxygen injected into copper has the effect of destroying the tensile strength and conductivity of the copper which defect has to be remedied in order to render the copper the purpose of de-oxidizing or expelling oxygen that has been introduced into the copper mostly by the operator for the purpose of expelling other impuritles contained in the copper. According to the present invention, however, oxygen is treated as other impurities and its contact with the copper is avoided as much as possible, the carbon therefore serving an entirely new function.

Apparatus of various kinds may be used in connection with my present invention, it being understood that the invention is not limited to any particular kind of apparatus.

In the accompanying drawing I have shown an apparatus as an example of one capable of use in connection with the lnvention. In this drawing 1 have shown a ladle 1 which receives the molten metal from the converters wherein the metal has been converted into metallic copper. This ladle is provided with trunnions 2 and a hanger 3 cooperates with the trunnions and 1S swung from an overhead crane, this arrangement enabling the ladle to be readily charged wlth molten metal from the converters and to be conveyed to the refining vessel 4 which has a brick or other refractory lining and may be rotatably supported on rollers 5 whereby it may discharge refined copper into suitable molding devices 6 which are indicated conventionally in the present instance. For this purpose the refining vessel is provided with a pouring spout 7 and it also has an opening 8 through which the molten copper from the ladle is introduced into the vessel. This opening 8 also serves in the present instance for the entrance of a tube which introduces hydrocarbon oil into the body of the bath of molten metal contained in the refining vessel.

The hydrocarbon oil, preferably crude petroleum, may be introduced by any suitable means into immediate or direct contact with the bath of molten copper, it being important, however, that this hydrocarbon oil should be introduced to the bath of molten copper at a point below its surface so that the hydrocarbon oil will come in direct contact with the molten copper and consequently this hydrocarbon oil will associate with as much oxygen and other impurities contained in the metal as the carbon contained in the oil is capable of absorbing. In the present instance I have shown a tube 9 for introducing the hydrocarbon oil into the body of the bath of molten metal. The lower end of this tube is submerged fora suitable distance below the surface 10 of ,the bath of copper, and this end of the-tube may be-protected by a refractory covering 11. The tube communicates with a pipe 12 which may be connected to a suitable source of hydrocarbon oil under pressure suflicient to cause the oil to flow from the tube into the body of the bath of molten copper. The hydrocarbon oil may be supplied to the tube by a pump or from a tank by gravity, the pressure under which the oil is fed being governed by the depth of immersion of the tube and the temperature of the charge, but this pressure should. always be sufficient to avoid carbonizing of the oil within that part of the tube which is submerged in the bath.

By introducing hydrocarbon oil into the body of the bath of molten copper as indicated above every atom of carbon contained in the oil is utilized in accomplishing the desired result of eliminating the impurities contained in the copper. The amount of oil used is controlled largely by the size of the charge in the refining vessel, the depth of immersion of the tube, and the degree of pressure under which the oil is supplied. A true condition is indicated by the absence of smoke on the surface of the charge, a bubbling of the metal and burning of the gases evolved.

After the bath of molten copper in the refining vessel has been refined, the vessel is tilted so as to discharge the refined copper into suitable casting means whereby it is cast into anodes, cakes or other forms, these being'preferably passed through a tank of water which removes any oxid scale formed and avoids any further oxidation of the copper. The copper is then ready for shipment to an electrolytic refinery for the extraction of precious metals.

I am aware of certain processes which have been heretofore proposed for the refining of copper by using hydrocarbon oil as a fuel to generate de-oxidizing gases. Such processes, however, have not to my knowledge proved commercially successful for the reason that in generating the gas by the burning of the oil, oxygen is absorbed from the atmosphere and this oxygen contained in the gases upon coming 1n contact with the copper defeats to a; considerable degree the refining action as oxygen is one of the impurities to be eliminated from the copper. ccording to the present invention on the ,contrary,'a hydrocarbon oil, preferably in the form of crude etroleum, is brought under pressure into immediate or direct contact with the molten metal by submerging the crude petroleum beneath the surface of the bath of metal so that the amount of crude petroleum which enters the bath will come in direct contact with as much oxygen contained in the metal as the carbon contained in the oil is capable of absorbing"and there is no oxy en-----introduced into the bath with this oil that would neutralize or defeat in part the purifying operation. Moreover, the present invention is very efiicient, as every atom of carbon is utilized in the operation of eliminating the 18 oxygen contained in the copper. Furthermore, according to the present invention, the combustion of oil takes place not in the atmosphere or before the oil reaches the bath of metal, but occurs owing to the heat of the molten metal and upon the moment of contact of the hydrocarbon oil with the metal below the surface of the bath.

I claim as my invention 1. .The hereindescribed improvement in the art of refining copper in an oxidized condition, which consists in introducing hydrocarbon oil free from oxygen into direct contact with the interior of a body or bath of molten copper While the latter is protected from oxidizing influences.

2. The hereindescribed method of refining copperwhich consists in introducing liquid hydrocarbon oil free from oxygen into the interior and below the surface of a body of the metal While in a molten state and while in an oxidized condition, and continuing such operation until all the impurities and the oxygen contained in the copper have been eliminated therefrom.

3. A method to increase the tensile strength and conductivity of copper and efiect an economy in the process of refining copper which consists in injecting hydrocarbon oil into a bath of the metal in an unoxidized condition for the purpose of eliminating all impurities contained therein.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

EDWARD 0. KING.

Witnesses:

Room H. HATCHETT, R. E. BLEWITT. 

